@EctoOne this sound more like something you would set in a gamelist file; I could add support for something like a <systemGroup> tag, where you'd put <system>s you want to handle together. Or a special system attribute, if we want to maintain strict ES2 compatibility.

@InsecureSpike well QML itself can be used for a lot of things, so it can look very complex at first. It can even be used for writing mobile games or web browsers, but fortunately for theming you won't have get familiar with all the components. In my opinion, the somewhat harder part is setting up the scrollable/moving elements (like a grid or a cover list) the way you want. After that, styling the elements is easy.

I'm going to write some tutorials when it gets released, in the meantime you might find this guide useful.

I'm really impressed. I've tried Attract Mode on my Pi, and it's kinda hard to use, at least for me, so I'm ready to see a new frontend.
I'm also excited to make some themes for this as well. :D
One thing though: Will it be an easy setup for the Pi? I don't want to go through the hassle of changing so much code and stuff.

@itsnitro in practice, a Pi release should "just work". The only problem is that Debian/Raspbian currently uses an outdated, 3 years old version of Qt, from which a bunch of features and optimizations are missing. As such, I'll include the required Qt libs with the releases, and also host the build tools and libraries too if you want to build on the board or cross compile.

gamelist reading and asset finding speed optimizations: currently loading ~1000 games, all with videos, box front, screenshot and logo takes less than 2 seconds on a Pi 3, and less than 10 seconds on a first gen Pi 1; these numbers may improve later

@meleu as soon as it's generally in a usable state, I'll open source it. There are some basic features I'd still like to work on before, like gamepad navigation, but I can make an alpha release this week or the next probably.